Fuel injection pump control



Sept. 12, 1950' L. E. JOHNSON 2,521,919

FUEL INJECTION PuuP comm. I 7 Filed March 19, 1947 Sheets-8116a 1 NINVENTOR. L L/ /fif 14m H AI'TORNEY p 1950 L. E. JOHNSON 2,5213 I9 FUELINJECTION PUMP CONTROL F iled March 19, 1947 2 Sheets-Sheet 2 IN VENTOR.

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Patented Sept. 12, 1 950 FUEL INJECTION PUMP CONTROL Lloyd E. Johnson,Peoria, Ill., assignor to Caterpillar Tractor 00., San Leandro, Calm, acorporation of California Application March 19, 1947, Serial No. 735,673

3 Claims. (Cl. 103-41) This invention relates to the operation andcontrol of fuel injection pumps of the kind used on compression ignitionengines and the like and pertains particularly to adjusting of meteringtype pump plungers where the plungers are aligned with each other as inan opposed cylinder engine.

In two cylinder engines, particularly where the cylinders are arrangedin opposed relationship, it is practical to employ a pair of opposedinjection pumps driven from a single centrally disposed cam. Theconventional metering type plunger employed in injection pumps isdesigned to be rotated as it operates and to meter fuel delivered to thecombustion chamber of the engine in response to its rotation or angularadjustment. Ordinarily, a single rack or gear meshing with gears fixedto a plurality of pump plungers serves to adjust all of the plungerssimultaneously. However, where two plungers operate in opposition toeach other they must be rotated or angularly adjusted simultaneously inopposite directions to efiect the required metering of fuel to thecylinder supplied by them. In any ordinary geared connection between twosuch plungers, the normal play or back lash in the gears preventsidentical adjustment of the plungers. The present invention is thereforeconcerned with means for connecting two pump plungers for simultaneousand identical angular adjustment in opposite directions. It will appearas the description proceeds, however, that the invention provides meansadaptable for connecting any two shaft like members for simultaneousangular adjustment where it is desirableto eliminate all possibility ofplay or back lash in the connecting means.

It is an object of this invention to provide means for connecting tworotatable shafts in a manner to effect identical but opposite adjustmentof both. Another object of the invention is to provide a fuel injectionpump control mechanism in which a pair of pump plungers may beaccurately adjusted together. Further and more specific objects andadvantages of the invention are made apparent in the followingspecification by reference to the accompanying drawings.

In the drawings:

Fig. 1 is a vertical sectional view through a fuel pump housing designedfor use with a two cylinder opposed type engine;

Fig. 2 is a view taken on the line 11-41 of Fig. 1 of the plungeradjusting means shown in Fig. l removed from the housing;

Fig. 3 is a section taken on the line IHIII oi Fig. 2; and

Fig. 4 is a section taken on the line IV-IV of Fig. 2.

Referring first to Fig. 1 of the drawings, a fuel pump housing is shownat III. A fuel pump assembly H is associated with each end of thehousing and these pumps are of more or less conventional construction.As shown at the left side of Fig. 1, each pump comprises a reciprocalplunger l2 normally urged to its retracted position by an assemblyincluding a spring l3 and having a plunger lifter M engageable by a caml 5 on a cam shaft 56. As the single cam I5 is interposed between bothof the plunger lifters it, it acts upon rotation of the cam shaft toefiect alternate reciprocation of the plungers l2 in their respectivecylinders. Fuel, from a source of supply not shown, is introducedthrough a pipe ll to manifold ll formed in the housing ill. Each of thepumps is in communication with the manifold it through an inlet passagel9, one of which is shown in Fig.

l 1. Upon retraction of the pump plunger it from its advanced positionshown in Fig. 1, fuel is admitted to the pump cylinder and uponsubsequent advancing of the plunger this fuel is directed under pressurethrough a conduit 28 to a fuel injection nozzle 2i illustrated asdisposed in the wall of the combustion chamber of the engine, a, por=tion of which wall is indicated at 22. Each of the plungers i2 is or theso-called scroll type designed for metering the quantity of fueldelivered to the combustion chamber of the engine upon each plungerstroke in response to angular adjustment of the plunger in the pumpcylinder. Such angular adjustment is ordinarily accomplished through theengine governor and the amount oi fuel delivered to the cylinders isvaried by changing the governor setting.

In the present construction each plunger is provided with a gear 23which is fixed to the plunger for imparting angular adjustment to it andeach of the gears 23 meshes with a segment gear 26. The segment gears 25are carried on shafts 25 and 26. The shaft 25 is shown as journaled inbearings 2i and 28 supported in the housing to, and the shaft 26,arranged parallel to the shaft 25, is supported for rotation in simi larbearings not shown. An end it on the shaft 25 is adapted for connectionwith a conventional engine governor so that the shaft will be angularlyadjusted in response to variations in setting of the governor, allthrough mechanism which is conventional and well known in the art. Uponangular adjustment of the shaft 25, the segment gear 2 3 imparts turningmovement to the mesh ing gear 23 and consequently effects angularadjustment of its plunger i2.

The present invention is particularly concerned with connecting togetherthe shafts 26 and 26 so that they :will rotate simultaneously inopposite directions to impart exactly the same angular adjustment toboth pump plungers. In order to accomplish this, the shaft 25 isprovided with a collar or drum 33, best shown in Figs. 2,

3 and 4, as fixed against rotation on the shaft by any sultablemeans,such as a tapered pin 30'. The shaft 26 is also provided with a drumpreferably but not necessarily made of two parts shown at 3| and 32.Interposed between the drum 30 and the drum comprising the two parts 3|and 32 are a pair of flexible metallic bands 33 and 34. Each of thebands as shown in Figs. 3 and 4 is secured at one of its ends, as by capscrews 36 and 31, respectively, to the drum 36, then passes around oneside of the drum, between the drums, and over the opposite side of thedrum made of the parts 3i and 32 to which its opposite end is secured asby similar screws 38 and 36, respectively. Thus, each band 33 and 34assumes an 8 like shape and the two bands serve to connect the two drumsand, consequently, the shafts 25 and 26 for simultaneous angularadjustment. As the drums are closely spaced and the connecting bands aretautly arranged, there is no free play or back lash during angularadjustment of the shafts and any adjustment imparted to the shaft 25 isimparted exactly equally but in the opposite direction to the shaft 26.As the bands 33 and 34 are oppositely disposed with respect to thedirection in which they are wound upon the drums, either one or theother of the bands is under tension when the shafts are rotated ineither direction.

One of the reasons for having a split or two part drum on the shaft 26is to enable the bands to beconveniently tightened. Each of the twoparts 3! and 32 of this drum is itself radially split and Joined by aset screw as indicated at 46 for the purpose of tightening it on theshaft 26. With this arrangement, the bands may first be secured at theirends to the respective drums as by the screws 36, 31', 36 and 33. As thescrews 33 and 33 occupy positions closely adjacent each other as shownin Fig. 2, they may be grasped together between a pair of pliers orsimilar tool while the drum portions 3| and 32 are loose on the shaft36. Thus, by applying pressure to the pliers, the screws will b drawntoward each other until both bands are placed under tension andtightening of the screws 46 with the parts 30 so held will effectclamping of the drum parts 3| and 32 tightly upon the shaft.

A further advantage of the two part drum on the shaft 26 andParticularly of having both drum parts free to rotate on the shaft isthat the bands may be tightened and secured without disturbing the phasepositions of the shafts 26 and 26. In practice the shafts 26 and 26 willbe set in proper phase position with respect to the operation of theplungers controlled bythem 4 through the gears 26. Then with the shaftssecurely held against rotation the bands can be tightened and the drumssecured to the shafts by screws 66.

As is. best illustrated iiiv Figs. 3 and 4, the spacing between theshafts 25 and 26 and the sizes of the drums are such that the spacebetween the peripheries of th drums on the two shafts just admits thethickness of the bands 33 and, 34. The purpose of this is to prevent anypossibility of transmitting bending stresses to the shafts while theyare being rotated and the bands are under tension. Were the drums to bemade smaller or th shafts spaced farther apart the tension on the bandswould be transmitted to the shafts in a manner to cause them to bearheavily in the bearing bushings which support them and would possiblyhinder their freedom of rotary movement.

I claim:

1. A device for connecting two parallel shafts for identical angularadjustment comprising a drum fixed to one shaft, a pair of drumsadjustably fixed to the other shaft, a pair of flexible metal bandsconnected at one of their ends to the first drum and having theiropposite ends fixed one to each of said pair of drums.

2. In combination with a fuel pump which comprises a housing, a pair ofpump plungers mounted for opposed operation in the housing, and gears onthe plungers for adjusting them angulariy, a gear meshing with eachplunger gear, separate shafts supporting the latter gears and journalledparallel to each other in the housing, and means connecting saidseparate shafts for simultaneous angular adjustment in oppositedirections.

3. In combination with a fuel pump which comprises a housing, a pair ofpump plungers mounted for opposed operation in the housing, and gears onthe plungers for adjusting them angularly, a gear meshing with eachplunger gear, separate shafts supporting the latter gears and journalledparallel to each other in the housing, and means connecting saidseparate shafts for simultaneous angular adjustment in oppositedirections, said means comprising drums on each shaft and flexiblestraps extending between and secured to said drums.

LLOYD E. JOHNSON.

REFERENOFS CITED The following references are of record in the file ofthis patenti UNITED STATES PATENTS

